Black azo dye and process of making same.



UNITED STATES PATENT OFFICE.

OTTO SOHST, OF HOOHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO THE FARE- WER-KE, VORMALS MEISTER, LUOIUS & BRUNING, OF SAME PLACE.

BLACK AZO DYE AND PROCESS OF MAKING SAME.

' SPECIFICATION forming part of Letters Patent No. 646,711, dated April 3, 1900.

Application filed March 9,1899. Serial No. 708,395. ($pecimens.)

To all whom it may concern:

Be it known that I, OTTO SOHST, Ph. D., a citizen of the Empire of Germany, residing at I-Iochst-on-the-Main, Germany,haveinvented certain new and useful Improvements in the Manufacture of new Monoazo Dyestuffs for Wool, of which the following is a specifica- 'tion.

naphtholdisulfonic acids.

I illustrate my process by the following example: Picramic acid is diazotized in the usual manner and the diazo compound is introduced into a soda alkaline solution of an equivalent quantity of 1 :8 :3 :6 acetylamidonaphtholdisulfonic acid. After standing for some hours the solution is salted out, pressed, and dried.

The dyestufi dyes wool black and may be developed to a dark olive green on treatment with chrome.

The dyes exhibit a much greater fastness to light than those obtained with the corresponding dyestufi from not acetylized amidonaphtholdisulfonic acid.

Having now described my invention, what I claim is- 1. The process for the manufacture of new monoazo-dyestuffs, which consists in combining diazotized picramic acid with acetylamidonaphtholsulfonic acids, substantially as described. V

2. As a new product the dyestufis obtained from diazotized picramic acid and acetylamidonaphtholsulfonic acid, being a dark powder, easily soluble in water and dyeing wool in black tints.

3. As a new product the dyestufi obtained -from diazotized picramic acid and 1 :8z3z6 acetylamidonaphtholdisulfonic acid, being a dark powder, easily soluble in water and dyeing wool in black tints.

In testimony that I claim the foregoing as my invention I have signed my name in pres ence of two subscribing witnesses.

OTTO SOHST.

ALFRED BRisBoIs. 

